This invention relates to improvements in a substantially planar diaphragm for use in an electroacoustic transducer and more particularly such diaphragm uses, in principle, the teaching of my U.S. Pat. No. 3,596,733. The diaphragm disclosed in said specification has been further developed in an effort to improve the quality of the sound when such diaphragm is used in a so called "flat loudspeaker". Test have shown that two basic concepts are important for achieving such result. One is that the vibratory movement of the sound producing sections of the diaphragm should be smooth on the active portions to avoid pronounced peaks and valleys in the response curve and the other is that the outer edge portion of the diaphragm should be so supported in a frame or casing that the active portion of the diaphragm may almost be considered as being floatingly supported.
Within these concepts several developments in different directions may be added to achieve particular results.